(1) Production of optically active alcohol: There have been known several processes for, production of optically active alcohols. For example, (1) symmetric hydrolysis of an carboxylate ester of racemic alcohol by an enzyme (Agric. Biol. Chem., 46, 757 (1982)); (2) asymmetric hydrogenation if a ketone as a precursor by an enzyme (Nippon Kagaku Zasshi, 1315 (1983)); and (3) asymmetric reduction of a ketone as a precursor by an asymmetric catalyst and hydrogen (J. Am. Chem. Soc., 101, 3129 (1979)). These processes are favorable to production of optically active alcohols but have their respective disadvantages. Process (1) needs an expensive enzyme and often involves difficulty in obtaining alcohols of high optical purity due to the enzyme's optical selectivity which greatly varies depending on the desired compound. Process (2) also needs an expensive enzyme and generally suffers the low enzymatic, activity. Process (3) needs an expensive asymmetric catalyst and involves difficulty in obtaining alcohols of high optical purity.
(2) Esterifying reaction: There have been known several processes for producing optically active alicyclic alcohol derivatives. For example, (1) reaction of a racemic cyclohexanol derivative with propionic acid (to give an ester), followed by enzymatic resolution by lipase (Synthesis 1137 (1990)); and (2) reaction of racemic alcohol with phthalic anhydride (to give a racemic carboxylic acid), followed by optical resolution by the aid of optically active .alpha.-phenylethylamine and subsequent hydrolysis to give an optically active alcohol (European Patent No. 656344). These processes are superior in production of optically active alicyclic alcohol derivatives but have their respective disadvantages. Process (1) needs an expensive enzyme and involves difficulty in obtaining alicyclic alcohol derivatives of high optical purity due to the enzyme's optical selectivity which greatly varies depending on the desired compound. Process (2) needs complex steps of synthesizing a phthalic acid derivative, forming a diastereomer salt with optically active .alpha.-phenylethylamine, and performing optical resolution.
(3) Oxidation of an alcohol to produce a ketone: There have been known several processes for producing an alicyclic ketone from in alicyclic alcohol by oxidation with a hypohalous acid. For example, (1) reaction of cycloheptanol with sodium hypochlorite in the presence of a quaternary ammonium salt (Tetrahedron Letter (1976), 2, 1641); (2) reaction a optically active menthol with sodium hypochlorite in glacial acetic acid (as a solvent) to give optically active menthone (J. Org. Chem., (1980), 45, 2030); (3) reaction of cycloalkanol with alkali metal (or alkaline earth metal) hypohalite at pH 6 or below in water and water-miscible solvent to give an alicyclic alcohol (Japanese Patent Laid-open No. 211629/1992); and (4) reaction of optically active 2-alkoxycyclohexanol with hypohalous acid or a source thereof to give an optically active 2-alkoxycycloalkanone (GB 2283971).
These processes have their respective disadvantages. Process (1) needs a quaternary ammonium salt (which adds to the production cost) and a complex step to separate the reaction product. Process (2) needs A complex step to separate the reaction product as the result of using glacial acetic acid as a solvent, although it efficiently yields the desired product without decrease in optical purity. Process (3) needs a complex step to separate the reaction product because of reaction in a water-miscible solvent. Process (4) gives rise to an undesirable by-product when the reaction is carried out in the presence of a ketone according to the most preferable embodiment. This by-product is a ketone with its .alpha.-position chlorinated. In the case where the ketone is acetone or methyl ethyl ketone, the by-product is .alpha.-chloroketone which is highly toxic to human bodies and possesses tearing properties. It aggravates the purity of the reaction product and has an adverse effect on the health of operators in the case of commercial production.
In addition, the optically active 2-alkoxycycloalkanone produced by the above-mentioned process decreases in chemical purity and undergoes racemization if it is stored at room temperature (about 30.degree. C.) after purification by distillation. Although the optically active .alpha.-substituted cyclic ketone is unstable, nothing is known about the method of stabilizing it.